Of Dr. Ackerman's passing, U.S. Education Secretary Arne Duncan said that "America's educators have lost a leader, and I have lost a friend and mentor."

When he was a young superintendent in Chicago, Duncan said, he looked to Ackerman for guidance "and learned a lot from her tenacity, courage and commitment to children."

She grew up in St. Louis, the oldest of five children born to a minister father and a teacher mother.

Her experience attending segregated schools, then becoming one of the only African American students at a mostly white high school, affected her profoundly. She often told of the day a white classmate refused to walk with her into their National Honor Society induction ceremony. Dr. Ackerman walked alone.

"While those were very difficult times, I think they helped shape who I am," Dr. Ackerman told The Inquirer in 2008. "They helped me understand the importance of a quality education, why resources are important. All of those experiences have made me a better leader, a better educator."

She earned a bachelor's degree from Harris-Stowe Teachers College, master's degrees from Washington and Harvard Universities, and a doctorate in educational leadership from Harvard.

By her own admission, Dr. Ackerman was an educator, not a politician, and that was a fact of which she was proud. That ultimately helped speed her departure from the district. The $905,000 severance she received rankled many in a district desperate for funding.

She could be a demanding boss who expected much of her staff and the district's 11,000 teachers. She took heat for her management style, financial stewardship, and even some curriculum decisions - but earned accolades for demanding equity for all children, and for her parent and community outreach efforts.

In 2010, she was named the top urban schools chief by the Council of Great City Schools.

Dr. Ackerman often said she wanted every student treated as she would have her two sons treated, and sympathized with working parents. She was a single mother, divorced from her sons' father and juggling a busy career and the care of her children. That helped shape her perspective as the leader of schools, she said.

In private - and often in public - she was warm, with a big smile and an easy laugh. She loved to sing and dance, particularly to Motown songs.

Dr. Ackerman began teaching in 1968, working in public schools in St. Louis, Chicago, and Seattle as a teacher, principal and administrator. She served as superintendent of the Washington school system from 1998 through 2000, then led the San Francisco district until 2006.

She was a professor at Columbia University Teachers College until her appointment as Philadelphia schools chief in 2008. After leaving the city, she formed her own educational consulting business in her new home of Albuquerque, where she moved to be near family.

She is survived by sons Anthony and Matthew Antognoli, siblings, and granddaughters. Funeral arrangements are not yet complete, a memorial service in Albuquerque will be scheduled, said Rev. Kevin Johnson, who has been asked by the family to give the eulogy.

Mayor Nutter, in a statement, described Ackerman as "a truly committed educator who demonstrated a profound passion for students and in particular the most disadvantaged students in our city. Through her leadership, Philadelphia took on the difficult, long-neglected task of turning around low-performing schools. Today, thousands of Philadelphia students are getting a better education thanks to her vision and advocacy. Her educational legacy will live on for many years through the initiatives that she championed."

Current Philadelphia schools chief William R. Hite Jr. also expressed sympathy to Dr. Ackerman's family "and all who loved her" in a statement.

"Dr. Ackerman devoted her life to children and public education, and in doing so, encouraged countless other individuals to commit their lives to teaching, learning and leading," Hite said in the statement. "For that, we are grateful. Our thoughts and prayers are with her family, friends and colleagues."